Perhaps the major effect of injector letdown is due to the injectors taking extreme return flow or back leakage. This is due to worn parts which permit extreme fuel to go through the diesel injector and to return back to the fuel system or tank. This reasons a drop in rail compression which consequences in hard starting or not starting at all. You should check these things: Fuel Composition Sensor Circuit Malfunction, Cylinder 1 Injector Circuit Low and Crankshaft Position Sensor B Circuit Malfunction. Fix the car engine properly and solve the car engine. Test the car engine when you need to know that the car engine is ok.